<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    body{ 
        padding:10px;
        margin: 10px;
    }
    .box1,.box2,.box3{
        height: 400px;
        width: 400px;
        border: 1px blanchedalmond dashed;
        float: left;
    }
    .box1{
        background-image: linear-gradient(to right,
        red,orange,yellow,green,blue,violet);
    }
    .box2{ 
        background-image: linear-gradient(to bottom right,red,yellow);
    }
    .box3{
        background-image:repeating-linear-gradient(pink,rgb(225, 0, 255) 10%,rgb(124, 101, 211) 20%);
    }
</style>
<body>
  <div class="box1"></div>
    <div class="box2"></div>
    <div class="box3"></div>
</body>
</html>